Glazing and the earth colours

Glazing is of critical importance to painting technique generally, so much so that it has been the principal manipulation or key to the evolution and development of oil painting for the last 500 to 700 years. It was introduced in Flanders, probably around the 15th century, and its culmination was realised in the late 19th-century Impressionist and Post-impressionist movements.

This aspect of the technique is foremost in Bill Morton’s day-to-day painting technique. It is used extensively throughout the execution of a painting and especially during the formative under-painting and under-glazing stages. Bill often states in a class environment that under-painting and under-glazing are as important and have as profound an effect on the final colour harmonies of a work as do the upper paint films.

All oil paint has a natural ‘inbuilt’ quality of transparency because of the linseed oil into which pigments are ground to make oil paint. Everyone knows the substance linseed oil. Even the cruder industrial grades have a degree of translucency. Linseed oil for artistic use is a much-refined version, free of mucilage and other impurities; it manifests as a clear translucent honey colour, a very transparent product. It is, consequently, of singular efficacy in its application as a paint vehicle because of the way that it imparts transparency to the pigments with which it is combined.

Earth colours are another factor integral to glazing. A very European device, they are at their best when used as under- and over-glazes for the pure colours. There are three basic sub-families—the earth reds, earth yellows and the umbers and browns.

Their very ‘earthy’ quality means they ‘temper’, or reduce, or harmonise, the rawness of the pure colours and they do this in ways no other colours can. Their properties of stability, permanence and light fastness and their (generally) higher oil content make them ideal for glazing. Their characteristics are such they are meant to be used for a ‘building-up’ of glaze on glaze, the very essence of what Kratochwil describes as ‘mother-of-pearl translucency’.